In recent years, development of information communication means has led to a service which uses various information communication means and distributes information such as content coming into widespread use. Due to the influence thereof, traffic amount of data communication has been increasing, and there is demand for means to handle this increasing traffic.
As one of the means, a technique has been proposed which is referred to as cognitive wireless communication, and which enables effective use of frequency by a terminal device and a base station recognizing the wireless environment and dynamically switching the communication system and frequency being used. With this cognitive wireless communication, practical implementation is being advanced for a frequency sharing system which uses frequencies allocated to existing wireless systems with a different wireless system.
For example, a frequency band which is allocated to an existing wireless system but is not used in that area or of which usage time is limited, may be used with a different wireless system. In particular, in the U.S.A., practical implementation thereof has been advanced as a technique to utilize available channels of TV broadcasting, which is so-called TV white space (for example, see NPL 1).
In NPL 1, a system is described in which a database (white space database: WSDB (White Space Data Base)) in which is registered available frequency and time slot for each area, is established, and wireless devices (TVBD (TV Band Devices)) refer to whether or not the frequency can be used, based on the current position.